Production of hydrocarbons from copyrolysis of plastic and tyre material with microwave heating

ABSTRACT

The present invention relates to the development of a microwave pyrolysis process for plastic materials selected from PE, PP, PS, PET, PVC and mixtures thereof in the presence of end-of-life tyres, or the pyrolysis residues thereof, or other carbon materials for the production of high added value pyrolysis oils containing over 50% by weight hydrocarbons distillable between 20 and 250° C. and a sulphur content less than 1% by weight.

FIELD OF THE INVENTION

The present invention relates to the field of methods of recyclingplastic materials, in particular to recycling of tyres at theirend-of-cycle (PFU), polyethylene (PE), polypropylene (PP), polystyrene(PS), polyethylene terephthalate (PET), polyvinyl chloride (PVC) andtheir mixtures.

STATE OF THE ART

In Italy, in 2008 were produced 3.5×10⁶ tons of plastic materials, and1.5×10⁶ of these were collected for disposal; in the same year 4.1×10⁵tons of tyres have been changed in motorcars and motor vehicles to berecycled. Polyethylene (PE), polypropylene (PP), polystyrene (PS),polyethylene terephthalate (PET), polyvinylchloride (PVC), polyurethanes(PU) represent up to 90% of the waste in plastics, specifically 60 to65% by weight are polyolefins PE and PP, between 10 to 20% by weight isPS and a quantity from 12 to 17% is PVC.

The increasing use of plastic material in recent years is giving rise tosome concern on the possibility of handling their disposal. Sinceplastic is replacing wood, glass, paper, and metal in many areas such asfor example in packaging and the manufacture of many articles, thiscontributes always increasingly towards the composition of the municipalsolid waste (MSW).

Handling of these large quantities of waste is an environmental issue ofenormous proportions that has required and requires a considerableeffort for the technological and scientific development of effectivesystems for their recycling and disposal.

Since the early 90's, interest in the disposal in dumping grounds hasshifted towards recycling, or at least energy recovery, thus paving theway for a new business sector: the industry of collecting, storing,cleaning, reprocessing, and manufacturing of renewed articles ready tobe introduced once again on the market.

Recycling of plastics has many aspects both technological and economicthat must be assessed. A first major problem concerns the variablecomposition of the waste, both for polymers types and for the presenceof additives and other substances such as glues, inks, labels, andorganic residues.

In addition, many thermoplastic materials are immiscible with each otherand recycling by simple reprocessing cannot lead to obtaining a materialwith good properties. Generally, remelting polymer mixtures worsenstheir physical properties, stability and processing. A recycle that isefficient with this type of approach provides use of homogeneous plasticmaterials or, when possible, use of large amounts of compatibilisers.

The technologies for recycling of plastic materials can be divided intofour categories:

-   -   Primary: regrind and reprocessing by moulding    -   Secondary: mechanical type processing of the plastic material.    -   Tertiary: feedstock for chemical processes or energy production.    -   Quaternary: incineration.

Each of these technologies has an important role in the recycling ofplastics, even if those processes capable of retaining the material withrespect to their incineration or disposal in dumping grounds are to bepreferred.

The tertiary recycling comprises all the heat treatments of plasticwaste that lead to chemical or petrochemical products of interest.Several technologies are available and currently used: pyrolysis,gasification, and hydrogenation. Heat treatments are extremely versatileand can be used in the recycling of all those materials otherwisedifficult to recover such as, for example, contaminated medical waste,polymeric residues of motorcars, and many other types of waste ofcomplex formulation. Selection of the recycling technique is made on thebasis of the purity of the waste, the chemical composition, and thenature of the additives. Pyrolysis processes convert the PE, PP, PS,PET, and PVC in oils to be used both by the petrochemical industry andin the existing refining processes.

By the term pyrolysis, reference is made to all those processes whereinenergy is supplied, generally in the form of heat, to an organiccompound to facilitate decomposition. This type of thermochemicaldegradation is an approach of considerable interest in the recovery andappreciation of post-consumer plastic materials. Pyrolysis is anendothermic process and is carried out at temperatures from 250° C. upto over 1,000° C. It leads into obtaining liquid and gaseous products,while certain solid products are constituted by carbon residues orinorganic non-pyrolisable fillers. These general considerations can beapplied both to the treatment of plastic materials and to the PFU

The five main categories of plastic materials, identifiable in urbansolid waste, are polyethylene (HDPE and LDPE), polypropylene (PP),polystyrene (PS), polyethylene terephthalate (PET), and polyvinylchloride (PVC). The pyrolysis process of these macromolecules leads intoobtaining a gas, a liquid, and generally a solid residue. Theproportions among these products are directly related to the type oftreated material, but also to the type of reactor and the processconditions, in particular on the temperature and heating rate used. Mostresearch has focused on the study of the pyrolysis processes of singlepolymers or mixtures thereof, to simulate the true composition of theMSW. Just as for the pyrolysis of individual PFU, also the pyrolysis ofpolymeric materials was carried out with various types of reactors:tubular, fluid-bed, autoclaves, and rotary ovens. The most promisingtechnology is that which employs a fluidised bed reactor, since itprovides excellent mass and heat transfer, ability to maintain aconstant temperature throughout the reactor (P. T. Williams, E. A.Williams, Energy & Fuel, 1999, 13, 188).

The microwave-induced pyrolysis is a process of new concept and wasintroduced for the first time by Tech—En Ltd (U.S. Pat. No. 5,387,321;U.S. Pat. No. 5,330,623). The plastic materials have very smalldielectric constant and loss factor. This implies that generally they donot absorb microwaves and therefore cannot heat at the pyrolysistemperature. The problem can be circumvented if in the mixture ofplastics, which are transparent to microwaves, an absorbent materialsuch as carbon is added. This type of pyrolysis then takes the name ofmicrowave-assisted pyrolysis. The energy transfer from the absorbingmaterial (carbon) to the polymer can be very efficient. This type ofheating causes formation of oxygenated organic compounds only for thequantities of oxygen present in plasticisers, additives, paints, inks,paper or other materials that make part of the treated products.

The present invention relates to this context on the research for newand always more efficient methods of recycling and reuse of plasticmaterials and of end-of-use tyres, which has as first objective,proposing the production of hydrocarbons. Purpose of the presentinvention is therefore a microwave pyrolysis process for the conversionof this waste into solid, liquid, and gaseous products which may findnew use in various industrial sectors: from the production of electricalenergy for combustion to the synthesis of plastic materials forpolymerisation.

In particular, to be able to obtain high added value liquid products(characterised qualitatively and quantitatively) for their use, possiblyeven direct, such as petroleum fractions, or for the extraction of theirmajority components (for example limonene, benzene, toluene, xylene, orother hydrocarbons prevailing therein).

DEFINITIONS AND ABBREVIATIONS

V_(M %): Mean percentage pyrolysis rate:

$V_{M\%} = {100\frac{\left( {M - M_{r}} \right)*M^{- 1}}{t}}$

wherein M is the total mass undergoing pyrolysis process; M_(r) is theless mass in the pyrolysis reactor; t is the duration of the pyrolysisexperiment.

V_(M risc): Mean heating rate of the mass undergoing pyrolysis.

$V_{M\mspace{14mu} {risc}} = \frac{T_{f} - T_{i}}{t}$

wherein T_(f) and T_(i) are the final and initial temperatures of thepyrolysis process and t is the duration of the experiment.

SUMMARY OF THE INVENTION

The present invention solves the above-mentioned problems by acopyrolysis process of plastic materials selected among PE, PP, PS, PVC,PET, and mixtures thereof in the presence of end-of-life tyres (PFU), ortheir pyrolysis residues or other material of carbon nature, throughmicrowave (MW), said method characterised in that:

(A) the vapours derived from the pyrolysis reaction are conveyed into afractionation system before being sent to a condensation system; or

(B) delivery of the MW is at such a power level as to obtain a meanpercentage pyrolysis rate (V_(M %)) less than or equal to 1.0/min and/ora mean heating rate (V_(M risc)) less than or equal to 10° C./min., inthe case pyrolysis induced by PFU; or delivery of the MW is at such apower level as to obtain a mean percentage pyrolysis rate (V_(M %)) lessthan or equal to 2.0/min and/or a mean heating rate (V_(M risc)) lessthan or equal to 15° C./min, in the case of pyrolysis induced by PFUpyrolysis residues.

Surprisingly, by the above process pyrolysis oils are obtained having asulphur content <1% by weight and a fraction greater than 50% by weightof distillable hydrocarbons comprised between 20 and 250° C.

When operating under conditions of variable modulation of the microwavepower, it is preferable to modulate the delivery in an increasingmanner.

From a macroscopic point of view, the oils obtained by the process ofthe present invention appear straw yellow in colour and are transparent,while those obtained under conditions other than the process of theinvention appear brown in colour and are turbid, or actually theysolidify at room temperature clogging the entire condensation system,but above all their hydrocarbon content with boiling points less than orequal to 250° C., do not exceed 30 to 40% by weight of the collectedliquid fraction.

The oils obtained by means of the process of the invention can be usedfor the recovery, through further refining, of raw materials such as forexample, limonene, benzene, toluene, xylene, or other hydrocarbonsprevailing therein. Actually, the oils obtained from the process of theinvention could be used directly as fuel for motor vehicles, or be mixedwith commercial fuels.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1—Experimental apparatus (Set-up A) used for the pyrolysis of tyrefragments and other plastic materials.

FIG. 2—Experimental apparatus with fractionation (Set-up B) used for thepyrolysis of tyre fragments and other plastic materials.

DETAILED DESCRIPTION OF THE INVENTION

The pyrolysis oils obtainable by the process according to the presentinvention also have PCS and PCI comprised between 33 and 48 MJ/kg;viscosity comprised between 0.49 and 2.80 cps; density less than orequal to 0.932 gr/cm³.

Preferably, the density of the pyrolysis oils obtained by the process isless than 0.850 gr/cm³ and the viscosity comprised between 0.80 and 2.20cps.

The process of the invention allows delivering the MW at maximum powerin case of the presence of a separation system or anyhow to a power suchas to obtain a V_(M %) greater than 0.5 min⁻¹ and/or a mean heating rate(V_(M risc)) greater than 3.5° C./min. In the absence of a fractionationsystem of the vapours, when using PFU in a mixture with plasticmaterials, it is preferable to operate to such a power level as toobtain a V_(M %) greater than 0.2 min⁻¹ and/or a mean heating rate(V_(M risc)) greater than 2.0° C./min. In the case of pyrolysis ofplastic materials induced by the presence of PFU pyrolysis residues, inthe presence of a fractionation system of the vapours, it is thenpreferable to deliver the MW to such a power level as to obtain aV_(M %) greater than 0.9/min which corresponds to a V_(M risc) greaterthan 8.0° C./min.

Preferably, according to the invention for the delivery of the MW, oneor more generators are used, operating at a frequency of 2.45 GHz.

By operating in the presence of a fractionation system, it is possibleto obtain pyrolysis oils which contain limonene, benzene, toluene orother single ring compounds in quantities at times even greater than 20%(as percentage area of the GC-MS analysis). The high quantity of singlering aromatic compounds, such as toluene, benzene, styrene, etc., makespyrolysis oils a possible resource from which to isolate the prevailingcompounds

In addition and preferably, the quantity of distillable hydrocarbons inthe range of 20 to 250° C. may reach and exceed 85% by weight of thepyrolysis oil.

The following are examples of fractionation systems according to theinvention:

-   -   Dephlegmator with air-cooling    -   Dephlegmator with column filled with Fenske, Rashig, Pall,        Lessing, and Cross-Partition rings    -   Dephlegmator with column filled with Berl, and Intalox saddles    -   Dephlegmator with column filled with glass beads of various        diameters (0.5 to 4 mm)    -   Dephlegmator with plate column        and their similar industrially viable systems.

Preferably, the ratio by weight between plastic materials and PFU variesbetween 1:1.5 and 1:4.0, while in the case of solid PFU pyrolysisresidue, use of said ratio varies between 1:0.5 and 1:1.

The yield of the pyrolysis process is always 100%.

Concerning the yields of pyrolysis oil in the process of the invention,these may vary between 5 and 90%. The yields of the solid product varybetween 10 and 60%, while those of the gaseous product vary between 4and 75%.

The sulphur content of the pyrolysis oils does not exceed 1.0%: theseliquid products, therefore, may fall into the class of low sulphurcontent fuel oils (BTZ, the limit of the sulphur content being 1% byweight), and also the results with respect to the heat power allow toinsert the liquid products in this class of commercial products. Thepossible use as diesel fuels for motor vehicles of liquid products,however, is limited in the light of the new regulation provisions on thesubject of fuel quality (from 1 Jan. 2009, the maximum sulphur contentin fuels for motor vehicles is set at 10 mg/Kg). In the course of thepyrolysis process, a sulphurated compounds sequestering agent, e.g.Ca(OH)₂, is used, causing a reduction of the sulphur content of thepyrolysis oils.

Use of a fractionation system has as a first effect reduction of thepyrolysis mean rate compared to the corresponding tests withoutfractionation. In particular, test 2 corresponds with test 9, and test 5corresponds with test 10 (Table 3).

The pyrolysis process with microwave heating has proved to be aneffective, selective, and environmentally friendly method for thethermal degradation of plastic materials in a mixture with tyres ortheir pyrolysis residues.

Effective because, compared to other processes with electric heating, orwith burners, the transfer of power to the mass to undergo thermaldegradation is immediate. It is not necessary to use even complexsystems such as fluidized bed reactors for a rapid transfer of heat.Treatment times are considerably reduced, even up to 90%, with respectto what is reported in the literature for conventional thermalpyrolysis.

Selective, since it allows obtaining pyrolysis oils with some basicfeatures both for their use as a fuel and as a source of petrochemicalindustry products. Specifically, it was possible to obtain pyrolysisoils with a density, viscosity, and variety of substances that make upthe mixture with high percentages of the distillable fraction typical ofpetrol and diesel oils. In addition, a discrete selectivity in theproduction of certain types of hydrocarbons of commercial interest hasbeen reached. For copyrolysis of polymeric materials such as HDPE, PP,PS, PET, and PVC, it has been possible to degrade them completely withyields comparable with those reported in the literature for heating thefluid bed reactor. For the PS, it has been possible to obtain largeamounts of styrene monomer, for PET up to 60% of the liquid product isconstituted by benzene. HDPE and PP were instead converted to mixturesof hydrocarbons. The pyrolysis of PVC has led into a rapid conversion ofmore than 90% of the chlorine content in the polymer in hydrochloricacid and in a subsequent degradation of the polymer chain intohydrocarbons. Even for the pyrolysis of these polymers, use of theexperimental set-up with dephlegmator (type B) has improved overall thecharacteristics of the liquid phase (density, viscosity, distillablefraction, and variety of the constituents).

Environmentally friendly, for the simple alternative that the processprovides for all the collection and dumping, incineration,waste-to-energy and conventional pyrolysis processes. It preserves theenergy and chemical content of polymeric materials by not oxidizing, butby depolymerising the macromolecules that constitute the charge bytransforming them into a potential substrate for the petrochemicalindustry. There is no dispersion in the environment either of waste orof hazardous or potentially hazardous burning residues, such assulphurous compounds and heavy metals.

The present invention will be better understood in the light of thefollowing embodiments.

Experimental Part

The pyrolysis experiments were carried out by means of a microwavelaboratory oven manufactured by Bi.Elle s.r.I. Company (No. 6, via HoChi Min, Modena, Italy). The oven consists of a sealed chamber, insideof which there is a turntable, four microwave generators outside theoven (characterised by a total power absorption of 8 KW (4×2 KW), thatdeliver a maximum power of 6 KW as an electromagnetic field operating ata frequency of 2,450 MHz) which communicate with the interior of thechamber through small windows located at half height of the chamber. Theposition and the method adopted of the microwave generators, of themagnetron type, ensure uniformity of the MW field inside of the entirechamber.

At the top of the chamber, the oven has a 40 mm diameter hole for theescape of gases and vapours.

In addition, to ensure real-time reading of the temperature inside thechamber, an infrared sensor, and a pyrometer were installed in thecentre of one of the inner walls.

The oven is operated by an electronic system which allows adjusting thedelivery of microwaves, even in continuity, by varying the electricalpower absorbed individually by each generator. The system allows thecreation of heating programmes, characterised by temperature steps,monitored by the infrared probe, with the control of the delivered powerand the duration of the step for each value of temperature.

However, it is not possible to set a constant and defined heating rate(° C./min).

The end-of-life (PFU), used for carrying out the pyrolysis experiments,were thermal tyres from a commercial motor vehicle, Michelin brand,Agilis model 81-195/65 R16C.

The CHNS elemental analysis only of the tyre compound has provided theresults reported in Table 1.

TABLE 1 CHNS elemental analysis of the Michelin Agilis tyre compound 81-195/65 R16C C (%) H (%) N (%) S (%) 88.19 7.23 0.23 1.76

The plastic materials subjected to pyrolysis process have been selectedon the basis of their presence in the RSU: polystyrene (PS),high-density polyethylene (HDPE), polypropylene (PP), polyethyleneterephthalate (PET) and polyvinylchloride (PVC). The PS necessary forthe tests was derived from foam PS used in packaging of materials. Thiswas first heated to above its softening temperature, about 60° C., andreduced in volume to be able to handle higher quantities in a lesservolume. The HDPE was recovered from a tank for solvents, suitablyfragmented for easy handling and durability in time thereof. The PP wasobtained from a container often dedicated to the disposal ofcontaminated material available in many laboratories. The PET wasobtained from 0.5 L bottles of mineral water. The PVC was purchased purefrom Sigma-Aldrich Company for minimising likely unforeseeninterferences of any plasticisers and additives.

The polymeric materials before being subjected to the pyrolysis processwere characterised through FT-IR and by means of CHN analysis.

TABLE 2 CHN analysis of polymers used in pyrolysis experiments(estimated values and measured values) C (wt %) H (wt %) CalculatedMeasured Calculated Measured PS 92.26 92.10 7.74 7.84 HDPE 85.63 85.3014.37 14.23 PP 85.63 85.14 14.37 14.61 PET 62.50 66.28 4.20 4.04 PVC38.44 38.23 4.84 4.65

Although the dimensions and power of the oven at our disposal couldenable carrying out the pyrolysis experiments both with entire tyres andnon fragmented plastic waste, for reasons of operating simplicity,reproducibility and safety, an experimental design was preferred withwhich to treat 300 to 500 gr. portions of materials both of only PFU anda mixture of PFU with plastic materials.

A tyre consists of several portions, characterised by relativequantities of reinforcement materials (steel) and different compounds,in relation to its function. In a typical experiment, cross sections ofabout 200 to 350 gr. of the tyre, further fragmented into pieces withsides of about 2 cm, were subjected to pyrolysis: a cross section can beconsidered a representative sample of an entire tyre since within thesample, all the portions of the tyre (tread, sides and bead) are foundin the same proportions with respect to the entire tyre.

Before undergoing pyrolysis, the plastic materials were fragmented inpieces with sides of 2 cm to enable introducing them easily into thepyrolysis apparatus, and to have sufficient homogeneity of the treatedsample.

In FIG. 1 is shown a system (Set-up of the A type) of the experimentalapparatus used for the execution of the pyrolysis experiments, while inFIG. 2 is shown the fractionation system (Set-up B)

The tyre fragments were introduced, after drying in an oven at 65° C.for 48 hours, within a 1 dm³ Pyrex glass flask, used as a reactionvessel (1): this latter was housed in the centre of the oven chamber, ata height corresponding to that of the emission windows of the MW fieldand of the infrared sensor.

The reaction vessel was connected, by means of Pyrex glass joints (2) toa Claisen head (3) with a thermometer (4) located outside the ovenchamber. A straight Pyrex glass joint (5) connected the Claisen head toa water-cooled straight cooler (6) (at room temperature), in turnconnected by a bend fitting (7) to a cooling coil (8) cooled at −10° C.,and with a thermostat. A collection system (9), installed downstream ofthe last cooler, collected the condensable liquid products. A liquidnitrogen trap (10) was connected to the flask collection system of theliquid phase allowing condensation of the vapours of the substanceswhich possibly, despite being liquid at room temperature, were draggedby the gas stream. Finally, the non-condensable part was collected in agas counter (11).

The experimental apparatus used for the execution of the pyrolysisfractionation experiments of the vapours in outlet from the MW oven(FIG. 2) had a set-up of the B type, which was similar to the system ofthe A type, but differed for a glass Pyrex vertical joint (2/a), locatedabove the joint (2) in outlet from the oven immediately before theClaisen head, filled with 4 mm diameter glass beads, or with anotherfractionation system among those reported in the paragraph on thefractionation systems, with the purpose, precisely, of fractionising thevapours in outlet from the oven. These vapours, passing through thefractionation column were deprived from that component which had aboiling temperature higher than the temperature of the vapours. Thissystem thus allowed dropping back into the reaction vessel the higherboiling compounds that had been dragged by the vapour stream.

The pyrolysis experiments were carried out in an inert atmosphere: theoperating conditions of the process; the operating variables and anymodifications to the system just described are reported and discussedsubsequently.

The degradation process started on average 30 seconds after the ignitionof the microwave generators regardless of the delivered power. Thevapours in outlet initially were white, which, with the increase of theflow of material in outlet from the oven became coloured up toyellow-brown. Initially, only a minimum fraction of the vapourscondensed before reaching the coolers.

Once completed the pyrolysis experiments, the equipment was disassembledas soon as room temperature was reached, and the products in thecondensed phase were taken directly in the vessels in which they werecollected (a one-neck ball for the liquid products, a flask wherein thereaction for the solid residue was carried out, and a gas counter forgaseous products). In this way, the introduction of artefacts in thesubsequent characterisations was minimised (the absorption ofatmospheric water from the solid residue and the release of the morevolatile components from the liquid product are the most likelyalterations).

The liquid products (pyrolysis oils) were centrifuged at 3,000 rpm foreliminating any solid materials in suspension. Samples of liquidproducts were transferred into 2 cm³ vials and sent to thedeterminations of the upper heat power and elemental composition (CHNSanalysis). The liquid products were also characterised by infraredspectroscopy and nuclear magnetic resonance spectroscopy, determinationsof the density and composition by GC-MS analysis, also carried out onthe centrifuged and homogenised liquid.

The solid residues were taken from the reaction vessel (a 1 dm³ Pyrexglass flask), fragmented, and homogenised in a mortar until obtaining apowder. Dust samples were then transferred into 2 cm³ vials and used fordetermining the upper heat power and the elemental composition (CHNSanalysis).

The gaseous mixtures produced during the pyrolysis process werecollected in a gas counter, connected to the nitrogen liquid traplocated immediately upstream in the process system. The volume of gaswas measured by means of a GFW Luzern water counter installed upstreamof the sampling system. The sampling of the gaseous mixtures for thesubsequent characterisations was carried out directly by the gas counterthrough a single 250 μL Hamilton Gastight syringe.

Measurement of the pyrolysis oil density was carried out by weighing themass of oil contained in a known volume under standard conditions(25.00° C., 1 atm.). Measurement of viscosity was determined on theliquid products by means of an Ostwlad viscometer thermostat at 25.00°C. in a silicone oil bath Julabo thermostat, ME-18V model. The upperheating power level (U.H.P.) was determined for the pyrolysis productsin the condensed phase, pyrolysis oil, and solid residue. In addition,from the U.H.P. it was calculated the lower heating power level(L.H.P.), by using the results of the elemental analysis carried out onthe same samples. The determination of the heat power of the condensedphases was carried out by the ESSE.TI.A. s.r.l. Company, at No. 121/123,viale dell'Arte della Paglia, 50058 Signa (FI), Italy, through a methodwhich consists in measuring the temperature before and after combustion,with excess oxygen, of a known mass sample in a calorimetric bombcompletely immersed in a calorimeter. The GC-MS analyses of the liquidproducts, for the identification of the substances constituting themixtures, were carried out through the GC-MS QP5050A Shimadzuinstrument, equipped with a quadruple mass analyser, and having aSupelco Equity 5 capillary column or 100 m. Petrocol.

All pyrolysis oils were subjected to fractional distillation, with thepurpose of separating fractions with characteristics (boiling point,density, and viscosity) comparable to petroleum products.

The pyrolysis experiments are shown below with unique identifyingnumbers: the pyrolysis products will be indicated by preceding theidentifying number of the experiment with letter G for gases, withletter L for liquids, and with letter S for solid residues.

Table 3 shows the conditions of the carried out experiments

TABLE 3 Pyrolysis experiments Charge subjected V_(Mrisc) Solid Gas Testto pyrolysis Delivered Tmax Duration Pyrolysed V_(M %) (° C./ (wt Liquid(wt Set-up of the liquid No. (ratio by weight) Set-up power (%) (° C.)(min) mass (g) (/min) min) %) (wt %) %) fraction 1 PFU A 50 495 39 233.31.27 12.18 50.45 39.21 10.34 brown turbid 2 PFU:HDPE = 2:1 A 50 493 33447.3 1.74 14.33 42.49 47.16 10.35 solid at room temperature 3 PFU:PP =2:1 A 50 599 39 385.4 1.66 14.85 35.29 56.00 8.71 brown turbid 4 PFU:PS= 2:1 A 50 557 60 439.4 1.00 8.95 39.90 56.10 4.00 brown turbid 5PFU:PET = 2:1 A 50 578 40 340.3 1.55 13.95 38.20 37.30 24.50 solid atroom temperature 6 PFU:PE:PP:PET = A 50 599 60 426.2 1.08 9.65 35.0549.70 15.25 brown turbid partly 2 4:5:5:2 solidified at room temperature7 PFU:HDPE = 2.4:1 A 25 × 180 min 599 261 362.0 0.25 2.22 35.52 45.8319.65 brown turbid  50 × 67 min  100 × 14 min* 8 PFU:PET = 3.9:1 A 25 ×111 min 599 248 313.5 0.21 2.33 48.29 26.34 25.37 brown turbid  50 × 89min  75 × 48 min 9 PFU:HDPE = 2:1 B  50 × 90 min 450 120 424.5 0.52 3.5838.00 42.71 19.29 yellow transparent 100 × 30 min 10 PFU:PET = 2:1 B 50440 70 296.9 0.81 6.00 43.35 29.36 27.29 yellow transparent 11 Solidresidue, test B 50 535 60 130.1* 0.94 8.58 56.23 7.85 35.92 yellowtransparent 5:PET = 1:1.35 12 PFU:PVC = 2:1 B 50 599 71 453.0 0.66 8.1553.16 19.70 27.14 yellow transparent 13 Solid residue, test B  50 × 20min 599 47 199.0* 1.83 12.32 13.92 12.25 73.83 yellow transparent 12:PVC= 1:1  75 × 10 min 100 × 17 min 14 Solid residue, test A  50 × 42 min578 59 196.3* 1.58 9.46 6.83 89.25 3.92 yellow transparent 4:PS = 1:2 75 × 5 m 100 × 12 min Set-up A: without fractionation system of thevapours in outlet from the oven; Set-up B: with fractionation system ofthe vapours in outlet from the oven. *Only polymeric material

Two fractions were collected in pyrolysis L7-L9, the second containedthe oils obtained after ignition of all the generators.

TABLE 4 characteristics of pyrolysis oils Density at 25° C. PCS PCIViscosity C H N S H/C ratio Test No. (g/cm³) (MJ/Kg) (MJ/Kg) (cps) (wt.%) (wt. %) (wt. %) (wt. %) (%)  1 0.889 48 46 n.d. 85.78 11.01 1.29 1.0 0.153  2 Nd ND ND nd 83.01 12.86 1.03 ND 0.155  3 0.831 46 44 2.79 82.0811.37 2.97 0.50 0.135  4 0.866 39 38 0.79 37.49 3.61 2.67 0.38 0.096  50.938 39 37 nd 66.05 8.37 3.89 0.90 0.127  6 Nd 33 30 nd 68.55 10.8 3.570.70 0.158  9-A 0.763 41 39 0.49 83.53 12.32 1.00 0.40 0.148  9-B 0.91045 43 1.31 43.60 6.06 1.97 0.30 0.139 10 0.856 40 39 0.85 57.71 5.455.81 0.60 0.094 11 Nd ND ND nd 79.45 6.14 3.64 ND 0.077 12 0.903 ND ND1.56 86.10 9.90 1.03 ND 0.115 13 0.932 ND ND 2.22 81.58 10.75 1.12 ND0.132 14 0.917 ND ND 0.90 70.24 5.94 0.96 ND 0.846

The GC-MS analysis of the pyrolysis oils has given considerableindications on the degradation of the polymeric charges. In thefollowing tables are given the main products of degradation.

TABLE 5 Prevalent substances in L3 (PFU - PP). N Attribution Composition(%) 1 Propane 0.89 2 2-Butane (E) 2.28 3 Pentane 3.80 4 1-Pentane 1.23 52-Pentane 1.14 6 2-Methyl-pentane 1.62 7 1-Hexane 2.54 8 Toluene 2.30 92,3-Dimethylesane 1.30 10 2,4-Dimethyl-1-heptane 12.47 111,3-Dimethyl-benzene 1.06 12 1,4-Dimethyl-benzene 1.22 13 Styrene 0.9014 7-Methyl-4-undecane 2.98 15 Limonene 3.14 16 Indene 0.91 172,4-Dimethyl-1-decane 1.79 18 4,6,8-Trimethyl-1-nonene 0.96 197-Methylundecano 3.40 20 7-Methyl-1-undecane 2.24 21 Elicosene 1.34 221-Tricosene 1.50 23 Octadecane 1.00 24 Eicosene 0.94 IDENTIFIED TOTAL52.95

The presence of chain fragments up to O₂₀ is evident. It is interestingnoting the presence of propane (0.89%), 2-methylpentane (1.62%) and2,4-dimethyl-1-heptane (12.47%) respectively monomer, hydrogenatedequivalent of the dimer and trimer of the propane thereof. Presence ofthese three molecules proves the efficient fragmentation of the PP.

TABLE 6 Prevalent substances in L4 and L14 (PFU - PS; carbon residue andPS). nAr: non aromatic; Ar: aromatic. N Attribution L4 L14 1 2-Butane(E) 1.73 2 1,3-Pentadiene 0.77 3 2-Pentane 0.62 4 Benzene 1.02 1.62 5Toluene 6.85 8.99 6 1,3-Dimethylbenzene 14.67 8.70 7 1,4-Dimethylbenzene0.91 8 Styrene 22.36 47.49 9 Cumene 3.12 10 α-Methylstyrene 7.83 13.3911 Limonene 1.46 12 1,3-Diphenilpropane 3.54 131,1′-(1.3-Propanedil)bis-benzene 2.80 14 4-Pentyl-benzene 5.06 151,1′-Cyclopropylidenebis-benzene 2.54 16 2-Phenyl-naphthalene 1.56IDENTIFIED TOTAL 64.88 92.15

Presence of styrene (22.36%), cumene (3.12%) and α-methylstyrene(7.83%), typical products of the degradation of polystyrene, demonstratethe successful and complete pyrolysis of the polymer. The totalconversion is supported by the absence of trimer styrene products.

In Table 7, are shown the most important products for the experiments ofcopyrolysis of PET and tyre. The pyrolysis carried out with theexperimental set-up of Type B (L10 and L11) is compared with thatcarried out with set-up A (L5). Pyrolysis 11 was carried out on amixture of PET and the residue of test 10. The substances obtained forthe pyrolysis of this mixture lead into obtaining only the products ofthe polymer degradation.

TABLE 7 Prevalent substances in liquid products L5, L10 and L11(PFU/carbon residue - PET). N Attribution L5 L10 L11 1 Acetaldehyde 1.172.06 2 1,3-Pentadiene 2.28 3 3-Methyl-1-hexane 1.60 4 Benzene 21.1517.44 57.61 5 Toluene 6.19 7.31 7.15 6 Cyclopentanone 1.11 73,5-Dimethyl-ciclohexane 0.96 8 1,3-Dimethyl-benzene 2.83 4.19 4.73 91,4-Dimethyl-benzene 2.44 3.44 10 Styrene 2.07 3.18 111,2-Dimethyl-benzene 2.26 0.88 12 Benzaldehyde 0.89 1.61 13Propyl-benzene 1.00 14 1,2,3-Trimethyl-benzene 3.10 1.95 15 Isolimonene0.86 16 α-Methyl-styrene 0.96 17 1,3,5-Trimethylbenzene 1.28 181-Ethy|-3-methyl-benzene 1.19 19 1,2,4,5-Tetramethyl-benzene 1.48 20Limonene 9.57 4.45 21 1H-Indene 1.61 22 Acetophenone 1.24 1.13 2.19 23Benzoiphormic acid 1.01 1.30 4.00 24 Ethyl benzoate 1.38 1.65 254-Methyl-acetophenone 2.20 1.52 6.84 26 Benzoic acid 3.39 2.10 27Biphenyl 2.41 0.97 3.40 28 4-formilbenzoic acid 0.46 292,6,10,14-Tetramethyl- 0.81 eptadecane IDENTIFIED TOTAL 68.71 58.0693.23

As expected, the substances attributed to gas chromatographic peaks forL15 are easily attributable to processes of degradation of the polymerchain of PET. In particular, the high presence of benzene may beattributed to the aromatic part of the polymer. The presence of suchspecies as biphenyl or 4-methyl-acetophenone is explained by thecoupling of two radicals; respectively between two phenyl radicals, andbetween the acetophenone radical and a methyl radical.

In Table 8 are shown the results of the GC-MS analysis of the twofractions obtained by the pyrolysis of HDPE with the experimental set-upof the B type. The products obtained by pyrolysis with the experimentalset-up of the A type are not shown because they are solid products atroom temperature. The second fraction was sampled with all generatorsignited at full power.

TABLE 8 Prevalent substances in the liquid products L9-A and L9-B (PFU -HDPE). N Attribution L9-A L9-B 1 2-Butane (E) 1.66 2 1-Pentane 0.90 0.773 Pentane 0.86 4 1,3-Pentadiene 1.42 5 1,4-Pentadiene 1.51 6 1-Hexane3.19 2.70 7 Hexane 1.23 8 Benzene 1.10 1.28 9 1-Heptane 2.70 2.19 10Heptane 1.91 11 Toluene 3.51 1.52 12 1-Octane 2.43 2.06 13 Octane 2.1014 1,3-Dimethylbenzene 2.08 15 1,4-Dimethylbenzene 2.81 161,2-Dimethylbenzene 1.62 2.33 17 3-Decane 2.96 18 Nonane 2.20 1.06 191-Tertbutil-1,5-octadiene 1.71 20 α-Methyl-styrene 0.94 21 3-Undecane4.24 3.43 22 Decane 2.03 1.61 23 1-Ethyl-3-methylbenzene 1.32 24Limonene 4.77 25 2-Tridecane 1.92 4.16 26 2,7-Dimethylottano 1.47 2.7227 3-Tridecane 0.88 4.41 28 Tridecane 3.60 29 2-Tetradecane 4.65 301-Methylnphatalene 0.57 31 Tetradecane 4.29 32 4-Tetradecane 4.84 334,8-Dimethyltridecano 4.97 34 1-Esadecane 4.35 35 2,6-Dimethyleptadecane5.44 36 1-Octadecane 2.52 37 C₁₉ 4.07 38 1-Octadecane 1.26 3910-Methylecoisane 3.05 40 5-Eicoisene 0.66 41 C₂₁ 1.98 42 C₃₆ 1.28 43C₃₆ 0.82 IDENTIFIED TOTAL 55.47 78.59

The two collected fractions are composed, in addition to the samesubstances identified for the pyrolysis oils L1 and L2, by increasingchain olefins and their hydrogenated equivalents, i.e., linearhydrocarbons from O₅ to O₃₆.

In Table 9, are shown the most important products for the copyrolysisexperiments of PVC and tyre. Pyrolysis 13 was carried out on a mixturebetween PVC and the residue of test 12. The substances obtained for thepyrolysis of this mixture lead into obtaining only the products of thepolymer degradation.

TABLE 9 Prevalent substances in the liquid products L12 and L13 (PFU -PVC). N Attribution L12 L13 1 t-Butylchloride 5.48 2 Benzene 18.51 18.563 2-Chloride-2-methylbutane 3.09 0.41 4 2-Chloride-3-methylpentane 1.040.2 5 Toluene 14.79 8.73 6 3-Chloride-3-methylpentane 1.91 7 Oct-3-ene2.28 8 6-Chloride-1-hexanole 2.46 9 4-Vinylcyclohexane 1.12 101,3-Dimethylbenzene 7.51 4.25 11 1,4-Dimethylbenzene 3.73 2.49 121,4-Dimethylbenzene 1.46 1.05 13 Styrene 2.44 0.46 141,2-Dimethylbenzene 4.18 3.44 15 2,4,4-Trimethyl-1-pentane 1.17 162,4,4-Trimethyl-1-esenane 1.15 17 1-Ethyl-2-methylbenzene 1.25 2.13 181,2,3-Trimethylbenzene 1.37 1.63 19 1,2-Dimethyl-3- 1.38methylencyclopentane 20 1-Ethyl-4-methylbenzene 0.75 1.48 211,3,5-Trimethylbenzene 1.15 1.57 22 sec-Butylbenzene 1.38 1.27 233-Methylcumene 3.29 24 Cyclopropyl-benzene 1.23 2.09 25 1,2,3,4,5,8-1.23 Hexahydronaphthalene 26 1-Methyl-1H-indene 0.4 1.41 274-Methyl-2,3-dihydro-1H-indene 1.03 28 2-Methyl-2,3-dihydro-1H-indene1.55 29 Naphthalene 2.01 4.01 30 2,6-Dimethyl-2,4,6-octatriene 1.03 31Benzocycloheptatriane 2.59 32 1-Methylnaphthalene 0.96 0.2 IDENTIFIEDTOTAL 87.47 62.83

All liquid products at room temperature were subjected to fractionaldistillation processes (see Table 10) in order to:

1. Obtain fractions with a boiling point comparable with that ofcommercial petroleum products.

2. Evaluate the possibility of isolating a single substance oralternatively obtain a fraction enriched in that substance.

TABLE 10 Fractioned distillation of pyrolysis oils: percentage of theproduct that distils depending on the boiling temperature. Total MaximumLiquid Duration V_(M%) Non-distilled distilled temperature of Product(min) (/min) residue (%) (%) distillation (° C.) L2 33 1.74 ND ND ND L339 1.66 77.16 22.84 195 L4 60 1.00 24.63 75.37 238 L5 40 1.55 72.0227.98 190 L6 60 1.25 ND ND ND L9-A 120 0.52  2.29 97.71 196 L9-B 1200.52 55.23 44.77 230 L10 70 0.81  4.37 95.63 258 L11 60 0.73 ND ND NDL12 71 0.61 41.47 58.53 217 L13 47 1.83 39.25 60.75 226 L14 59 1.5813.28 86.72 169

The distilled fractions, regardless of the distilled amounts, haveboiling temperatures typical of commercial petrol.

All fractions obtained from each distillation were analysed by GC-MSwith the purpose of determining the majority substances in each onethereof. In the following tables, are shown the three majoritysubstances in each fraction, with related percentages identified by thegas chromatography analysis.

TABLE 11 Prevalent substances in the fractions obtained from thedistillation of L3. Temperature range Composition Fraction (° C.)Substance (%) 1 20-40 2-Methylbutane 18.70 2-Methylpentane 14.502-Methyl-1-pentane 19.58 2 40-50 2-Methylbutane 12.17 2-Methyl pentane15.45 2-Methyl-1-pentane 25.12 3 50-63 2-Methylbutane 7.962-Methyl-1-pentane 11.21 Benzene 7.78 4  63-133 Toluene 8.194-Methylheptane 6.59 2,4-Dimethyl-1-heptane 65.50 5 133-1482,4-Dimethyl-1-heptane 72.62 1,4-Dimethylbenzene 6.62 4-Methyl-1-octane11.33 6 148-155 2,4-Dimethyl-1-heptane 45.16 1,4-Dimethylbenzene 5.724-Methyl-1-octane 26.65 7 155-181 2,4-Dimethyl-1-heptane 7.414-Methyl-1-octane 26.65 Limonene 15.98 8 181-195 2,8-Dimethylundecane7.33 Limonene 22.80 7-Methyl-1-undecane 9.97

TABLE 12 Prevalent substances in the fractions obtained from thedistillation of L4. Temperature Composition Fraction range (° C.)Substance (%) 1 20-40 2-Butane (E) 12.96 1,3-Pentadiene 20.733-Methyl-1-esane 14.40 2 40-59 Toluene 42.58 1,3-Dimethylbenzene 17.65Styrene 11.15 3 59-63 Toluene 28.31 1,3-Dimethylbenzene 33.63 Styrene34.36 4  63-164 Toluene 11.73 1,3-Dimethylbenzene 36.54 Styrene 48.79 5164-176 1,3-Dimethylbenzene 27.95 Styrene 55.15 α-Methyl-styrene 8.87 6176-201 1,3-Dimethyl-benzene 9.95 Styrene 36.06 α-Methyl-styrene 33.66 7201-220 1-Ethyl-4-methylbenzene 13.50 Limonene 8.131-Methyl-4-(1-methyl-ethenil)- 5.87 benzene 8 220-2385-Methyl-2.3-dihydro-1H-indane 5.74 3-Methyl-1H-Indane 3.62Pentylbenzene 4.04

TABLE 13 Prevalent substances in the fractions obtained from thedistillation of L5. Temp. range Composition Fraction (° C.) Substance(%) 1 25-45 n.d.* n.d. 2 45-62 2-Pentane (E) 7.59 3-Methyl-1-esane 5.22Benzene 74.88 3 62-77 2-Pentane (E) 3.75 Benzene 84.72 Toluene 11.53 4 77-150 1,3- 15.87 Dimethylbenzene 1,4- 16.94 Dimethylbenzene Limonene16.90 5 150-180 Styrene 4.73 5-Ethyl-1- 11.98 methylthiophene Limonene42.27 *fraction 1 was a negligible quantity and was not analysed

TABLE 14 Prevalent substances in the fractions obtained from thedistillation of L7-A. Temperature range Composition Fraction (° C.)Substance (%) 1 20-40 1-Hexane 6.14 Hexane 3.73 Benzene 4.15 2 40-60Benzene 6.13 Cycloheptane 6.00 Toluene 6.14 3 60-74 Toluene 7.631-Octane 6.09 2,4-Dimethylheptane 5.40 4  74-158 1,4-Dimeti-benzene 5.791-Nonane 8.18 nonane 5.35 5 158-170 1-Decane 6.56 1-Methyl-3-(1- 7.49methylethyl)benzene Limonene 5.86 6 170-185 1-Methyl-3-(1- 6.78methylethyl)benzene 1-Undicane 7.14 Undicane 6.85

TABLE 15 Prevalent substances in the fractions obtained from thedistillationof L7-B. Temperature range Composition Fraction (° C.)Substance (%) 1 20-55 1-Hexane 6.31 1-Hheptane 5.19 Heptane 3.90 2 55-146 Styrene 14.22 1-Nonane 9.20 1-Decane 11.42 3 146-176 Styrene10.19 1-Nonane 6.76 1-Decane 12.25 4 176-245 1-Undicane 5.17 1-Dodicane5.12 Dodicane 5.01

TABLE 16 Prevalent substances in the fractions obtained from thedistillation of L8-A. Temperature range Composition Fraction (° C.)Substance (%) 1 20-40 2-Pentane 4.49 Dimethyl oxalate 5.653-Methyl-2-pentane 5.12 2 40-60 Benzene 13.47 1-Ethylcyclohexane 3.47Toluene 8.18 3 60-76 Benzene 7.44 Toluene 15.07 1,3-Dimethylbenzene 6.434  76-158 Toluene 5.29 1,3-Dimethylbenzene 10.66 1,4-Dimethylbenzene12.26 5 158-170 1,3-Dimethylbenzene 7.36 1,3,5-Trimethylbenzene 5.161,2,4,5- 5.61 Tetramethylbenzene 6 170-269 n.d.* ND *Fraction 6 wassolid at room temperature and was not analysed

TABLE 17 Prevalent substances in the fractions obtained from thedistillation of L8-B. Temperature range Composition Fraction (° C.)Substance (%) 1 20-40 3-Hexane 5.24 Benzene 27.17 Toluene 6.82 2 40-48Benzene 48.40 1-Heptane 5.69 Toluene 16.48 3  48-158 Toluene 11.081,3-Dimethylbenzene 17.78 1,4-Dimethylbenzene 16.00 4 158-1701,2,3-Trimethylbenzene 10.46 1,2,4-Trimethylbenzene 6.011,3,5-Trimethylbenzene 5.03 5 170-252 1-Methylnaftalene 4.952-Methylnaftalene 3.21 Biphenyl 4.26

TABLE 18 Prevalent substances in the fractions obtained from thedistillation of L9-A. Temperature range Composition Fraction (° C.)Substance (%) 1 20-45 1,3-Pentadiane 10.87 1,4-Pentadiane 10.84 3-Hexane18.81 2 45-65 1,3-Pentadiane 7.33 3-Hexane 20.60 Hexane 8.95 3  65-1071-Heptane 11.66 Heptane 8.18 Toluene 11.92 4 107-152 Toluene 9.921-Octane 10.45 1,4-Dimethylbenzene 10.71 5 152-178 3-Decane 9.113-Undicane 9.46 Limonene 10.25 6 178-196 3-Undicane 14.70 Limonene 27.412-Tridecane 11.80

TABLE 19 Prevalent substances in the fractions obtained from thedistillation of L10. Temperature range Composition Fraction (° C.)Substance (%) 1 20-75 1,3-Pentadiene 5.88 3-Methyl-1-hexane 5.38 Benzene73.62 2 75-80 Toluene 12.86 1-Octane 27.14 2-Decane 15.05 3  80-102Benzene 28.17 Toluene 41.65 1,3-Dimethylbenzene 9.91 4 103-150 n.d.*n.d. 5 150-180 n.d.* n.d. 6 180-255 1,2,4,5- 6.17 TetramethylbenzeneLimonene 18.94 Ethyl benzoate 5.81 *Fractions 4 and 5 were negligiblequantities and were not analysed

TABLE 20 Prevalent substances in the fractions obtained from thedistillation of L12. Temperature range Composition Fraction (° C.)Substance (%) 1 20-40 t-Butylchloride 17.00 Benzene 61.612-Chloride-2-methylbutane 8.75 2 40-44 Benzene 41.872-Chloride-2-methylbutane 8.30 Toluene 22.54 3  44-145 Toluene 50.133-Chloride-3-methylpentane 5.56 6-Chloride-hexan-1-ole 4.73 4 145-180Toluene 11.64 1,3-Dimethylbenzene 17.21 1,4-Dimethylbenzene 14.09 5180-217 n.d. 4.05 1,2,3,4,4a,8a- 3.51 Hexahydronaphthalene Decaline 4.00

TABLE 21 Prevalent substances in the fractions obtained from thedistillation of L13. Temperature range Composition Fraction (° C.)Substance (%) 1 20-40 Benzene 38.33 3,3,4-Trimethylesane 4.62 Toluene5.86 2 40-48 Benzene 33.34 3,3,4-Trimethylesane 6.88 Toluene 12.14 3 48-145 1,3-Dimethylbenzene 6.92 1,4-Dimethylbenzene 9.021,2-Dimethylbenzene 8.23 4 145-174 1,2,3-Trimethylbenzene 5.601-Ethyl-4-methylbenzene 4.55 1,3,5-Trimethylbenzene 5.89 5 174-226 n.d.2.48 n.d. 5.24 n.d. 2.47

TABLE 22 Prevalent substances in the fractions obtained from thedistillation of L14. Temperature range Composition Fraction (° C.)Substance (%) 1 20-56 Benzene 13.73 Toluene 29.75 Styrene 36.80 2 56-74Toluene 23.33 1,3- 13.78 Dimethylbenzene Styrene 51.39 3 74-77 Toluene15.97 1,3- 14.23 Dimethylbenzene Styrene 60.96 4  77-151 1,3- 12.22Dimethylbenzene Styrene 69.68 α-Methylstyrene 10.80 5 151-169 Styrene50.50 α-Methylstyrene 41.59

It was not possible to isolate in any fraction a single substance, butfractions enriched up to more than 70%.

In the above-mentioned pyrolysis of plastic materials, in the presenceof a suitable quantity of the solid residue of a previous PFU pyrolysis,the obtained results are similar to those of PFU/plastic materialspyrolysis, taking into consideration that in the collected fractions,the products of PFU decomposition are not present.

All gaseous mixtures obtained in the experiments are colourless,transparent and with an unpleasant smell of composition similar to thatobtained from the pyrolysis of only PFU

In the gaseous products of pyrolysis of PFU/PET, or residue carbon/PET,a considerable amount of acetaldehyde was found.

In the gaseous products of pyrolysis of PFU/PVC or residue carbon/PVC,HCl was present.

TABLE 23 Prevalent substances in gaseous products Substance G1 C1 e C276.79 Propylene 3.70 1-Butane 10.10 2-Butane-trans 0.94 2-Butane-cis0.56 2-Methyl-1-butane — n-Pentane 0.75 Isoprene 3.60 2-Hexane — TOTAL96.44

The solid products obtained from copyrolysis of polymeric materials andtyres in appearance are identical to those obtained by simple tyrepyrolysis, that is, the solid residue in the reaction vessel at the endof the experiment, is a friable material, black in colour, of the samesizes of the initial tyre fragments. The material after fragmentationand homogenisation is as a black powder mixed with metal wires removablewith a simple magnet. The solid residue of tests 2 to 10, and 12,therefore, is the same as that obtained from a pyrolysis test of onlytyres (test 1).

In tests 11, 13 and 14, the PFU has been replaced with the solid residueof the previous test. Solid S11 is a single solid compact block, butfragile. Notwithstanding, the different appearance from other friablesolid products, the conversion of PET is practically total; the amountof solid residue is only increased by 2%, compared to the initial PET.

The solid products, after having been deprived of the metal wires with amagnet, are composed mainly of carbon (Table 24). The presence ofhydrogen is minimal and in samples from S2 to S6 is attributable to theincomplete volatilisation of all the substances containing hydrogen. Insamples from S9 to S13 the majority concentration of hydrogen can beexplained by the presence of oil which, in the last phase of theexperiment, was present in the dephlegmator and returned to the reactionflask

TABLE 24 CHNS elemental analysis of solid products Solid C H N S H/C *100 Product (wt %) (wt %) (wt %) (wt %) Ratio S1 82.31 0.83 0.48 2.01.01 S2 86.67 0.780 0.49 ND 0.90 S3 87.74 0.29 0.44 1.7 0.33 S4 ND ND ND0.2 ND S5 87.72 0.36 0.80 2.3 0.43 S6 87.10 0.517 0.25 1.8 0.58 S9 87.241.27 0.00 1.3 1.46 S10 87.36 1.17 0.17 1.3 1.34 S11 83.79 1.12 0.17 ND1.34 S12 44.65 0.98 0.12 ND 0.022 S13 62.77 1.60 — ND 0.026 S14 80.211.15 0.68 ND 0.014

The sulphur content reaches a minimum in S4. For the other solidproducts, the values do not vary from those obtained for the pyrolysisresidues of only PFU (S1). All the pyrolysis is nearly complete and thecontribution by mass of the residue of each polymeric material mixedwith the tyre is minimal

1. A process comprising subjecting plastic materials such aspolyethylene (PE), polypropylene (PP), polystyrene (PS), polyethyleneterephthalate (PET), polyvinyl chloride (PVC) and mixtures thereof, topyrolysis by way of irradiation with microwaves (MW) said plasticmaterials being mixed with end-of-life tyres (PFU), or the solidpyrolysis residues thereof or other carbon materials, said processcharacterised in that: (a) the vapours derived from the pyrolysisreaction are conveyed in a fractionation system before being sent to acondensation system; or (b) the delivery of the MW is at such a powerlevel as to obtain a mean percentage pyrolysis rate (V_(M %)) of lessthan, or equal to, 1.0/min and/or a mean heating rate (_(VM risc)) ofless than, or equal to, 10° C./min, in case of pyrolysis induced by PFU;or delivery of the MW at such a power level as to obtain a meanpyrolysis rate (V_(M %)) of less than or equal to 2.0/min and/or a meanheating rate (V_(M risc)) of less than or equal to 15° C./min, in thecase of pyrolysis induced by PFU pyrolysis residues and the vapoursderived from the pyrolysis reaction are directly sent to a condensationsystem, without being conveyed in a fractionation system before beingsent to the condensation system; for obtaining pyrolysis oils having acontent greater than 50% by weight of hydrocarbons distillable between20 and 250° C. and having a sulphur content less than 1% by weight. 2.The process according to claim 1, subparagraph (a) wherein thefractionation system is selected from: Dephlegmator with air-coolingDephlegmator with column filled with Fenske, Rashig, Pall, Lessing, andCross-Partition rings Dephlegmator with column filled with Berl, orIntalox saddles Dephlegmator with column filled with glass beads ofvarious diameters (0.5 to 4 mm) Dephlegmator with plate column a similarindustrially viable system.
 3. The process according to claim 2 whereinthe delivery of the MW is at such a power level as to obtain a V_(M %)greater than 0.5/min and/or an mean heating rate (V_(M risc)) greaterthan 3.5° C./min.
 4. The process according to claim 1 wherein theplastic material/PFU weight ratio varies between 0.25 and 8.0, while inthe case of the use of plastic materials/solid PFU pyrolysis residue,said ratio varies between 1.0 and 2.0.
 5. The process according to claim1, subparagraph (b) wherein _(VM %) is greater than 0.2 min⁻¹ and/orV_(M risc) is greater than 2.0° C./min, when PFU is are used in themixture with plastic materials; or in the case of pyrolysis of plasticmaterials induced by the presence of PFU pyrolysis residues, thenV_(M %) is greater than 0.7/min, which corresponds to a V_(M risc)greater than 8.0° C./min.
 6. The process according to claim 1 wherein tolower the sulphur content in pyrolysis oil, a sulphurated compoundssequestering agent is used during the process.
 7. The process accordingto claim 1 wherein for pdelivery of the MW, one or more generators,operating at a frequency of 2.45 GHz, are used.